ducted aircon
it's a lot cheaper to run than many realise
you let it run 24/7 & the compressor only comes on for short periods to maintain the desired temperature.
i constantly see morons with airconditioning who shut it down as soon as they feel cool, then an hour later they switch it back on again as they are getting warm again.
these are the ppl that will say it is expensive to run, not understanding the difference between maintaining a certain temperature and repeatedly having to achieve that same temperature for short periods.